The main objective of the proposed research is the continuation of the formulation of an internationally acceptable, uniform terminology of the anatomy of birds covering all of the organ systems at macro- and mesoscopic levels. The ultimate goal of the project is the publication and distribution of Nomina Anatomica Avium, a handbook that will correspond to, and supplement, similar nomenclatures already established for man (Nomina Anatomica, 1955, 1963, 1966) and the domestic mammals (Nomina Anatomica Veterinaria, 1968, 1973). The project has advanced substantially toward completion since its inception, having progressed past the mid-point. The research is carried on by the International Committee on Avian Anatomical Nomenclature (ICAAN), an organization of over seventy scientists of twenty different nationalities. These members of ICAAN have assumed the responsibility of developing the Avain Anatomical nomenclature; the crededentials of these experts represent a side spectrum of specialities in avian biology. ICAAN is made up of fourteen Subcommittees each dealing with an organ system or part of a system, e.g., Angiologia, Systema nervosum centrale, Systema respiratorium, etc. By means of dissections, laboratory observations, and literature research members of each Subcommittee have prepared lists of names of nerves, vessels, ligaments, parts of heart, features of bones, body regions and parts, etc. These lists have been studied, criticized, revised, reconciled, and refined extensively. As of this time the third generation of lists (Provisional Lists) with accompanying annotations, illustrations, and bibliographic references are being circulated preparatory to their consideration in Liverpool, U.K. in July, 1974 at the Second General Meeting of ICAAN. The definitive Final Lists will be presented at the meetings of the World Association of Veterinary Anatomists in Greece, summer of 1975, and subsequently made ready for publication.